This application relates to a brake shoe assembly having a sensor for determining when the brake lining of the assembly has worn below a critical thickness and when the temperature of the brake lining has exceeded a predetermined temperature threshold.
Most motor vehicles include a brake system having a set of brake shoe assemblies for retarding the rotation of the wheels of the vehicle when the brakes are applied. Typically, each brake shoe assembly includes a brake lining made of a friction material which gradually wears away during brake applications. After numerous brake applications, the brake lining wears below a critical material thickness and, therefore, should be replaced. As a result, the brake lining must be periodically inspected for excessive wear. To eliminate time-consuming and costly visual inspections of the brake lining, the prior art has taught several types of brake lining wear sensors for indicating when the brake lining must be replaced.
One type of brake lining wear sensor, sometimes referred to as a wire loop sensor, indicates when the brake lining has worn below a critical thickness. Although prior art wire loop sensors are relatively inexpensive and simple, they do not indicate the temperature of the brake lining. Accordingly, it would be desirable provide an inexpensive and simple sensor for detecting both when the brake lining has worn below a critical thickness and when the temperature of the brake lining has exceeded a predetermined temperature threshold.